The regulation of proteolysis is considered to be a pivotal requirement in the maintenance of homeostasis in all living organisms. This delicate balance, however, is continually being challenged by a triad of factors which may cause an increase in proteolysis, of primary importance being those effects exerted by proteinases from non-host systems. Thus, there is enormous interest in examining not only the mechanisms by which host enzymes and inhibitors interact but also how proteinases from viruses, pathogenic bacteria, and parasites deregulate tightly controlled biochemical pathways, such as the coagulation, complement, kallikrein/kinin, and cytokine systems, during inflammatory episodes. Significantly, one can now extend such studies into the plant field where it is now possible to understand not only haw proteinase-proteinase inhibitor synthesis is induced but also haw it may be enhanced in order to aid in both plant defense and food production. This symposium has been designed to bring together a broadly-based group of scientists whose primary interests involve an understanding of how proteinases and inhibitors from all living organisms and viruses function in normal and pathological states, and how the latter may be rectified by the use of either natural or synthetic inhibitors. It has also been organized in order to attract both graduate students and young M.D. and Ph.D. research scientists to a meeting place where they may become more familiar with a rapidly expanding area within the biosciences which is already of premier importance in pathobiochemistry, nutritional biochemistry, plant biochemistry, and virology.